Question about Cars & Trucks
Usually a PCM just makes the grounds, I don't know if the BCM does the same or what? If I ran power to the pump wire and or made the ground good, would it cause a problem elsewhere? I've been wrenching for 40 years but when they started adding PCM's BCM's, TCM's....it's not as easy as just running a fresh piece of wire from the fuse to the part like it used to be. It's kind of overwhelming how many wires are in a harness anymore, searching for a little cut, pinch or melt can be impossible unless you take the whole car apart! LOL So, anyway, if you can help me on that, I'd appreciate it, I'm not sure what will happen if I just make the ground or run power to it. I don't want to fry the BCM or anything. Thanks, Wayne
GM Fuel Pump Relay Testing Fuel Pump Electrical Circuits Description and Operation
If your missing B+ voltage somewhere , you have high resistance in the circuit ! Do you know how to do voltage drop testing to find high resistance ? If you been wrenchen for 40 years this is something you should know ! Mastering Voltage Drop Testing with Pete Meier and Jerry Truglia
Posted on Dec 08, 2016
Testimonial: "Agreed, I should. 40 years ago I was 10, mom was coming home from work and I could hear the back brakes grinding. She asked, "can you fix that?" I said, "do I have a choice". LOL So I STARTED wrenching 40 years ago I should have said. I've been doing it on and off since I was a kid but mostly parts changing. Thanks for the vids and info, VERY helpful. Wayne"
Hi Wayne, I'm sure your a better mechanic than I, I just looked at your wiring diagram. The control side of relay, that little coil looking sign, it needs voltage and ground, the ground appears to be chassis ground, the voltage comes from pcm. The load side of relay is that line with arrow-head, when relay is energized, that arrow-head moves to other terminal and carries voltage to pump motor. If you use a proper jumper wire on the two terminals, load side of relay, one of those terminals should be hot, if wiring and pump motor are ok, the pump should run. Your bypassing the control side of relay by using jumper.
Posted on Dec 08, 2016
Testimonial: "Ok, it turns out the relay is not activating. If the G6 connection is ground, that would mean I should be getting a positive connection to J7 in order to activate the electromagnet. Am I correct about that? If so, what is that image of G103? Is that body ground? And for the J7 positive connection, where does power come from? Full time positive? PCM positive? I pulled the fuse block apart and found the grey wire but not the dark green/white."
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Posted on Jan 02, 2017
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